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TRANSCRIPT
Chapter Introduction
Lesson 1 Forms of Energy
Lesson 2 Energy Transformations
Lesson 3 Energy Resources
Chapter Wrap-Up
What do you think?
Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements.
1. A fast-moving baseball has more kinetic energy than a slow-moving baseball.
2. A book sitting on a shelf has no energy.
Do you agree or disagree?
3. Energy can change from one form to another.
4. If you toss a baton straight up, total energy decreases as the baton rises.
Do you agree or disagree?
5. Nuclear power plants release many dangerous pollutants into the air as they transform nuclear energy into electric energy.
6. Thermal energy from within Earth can be transformed into electric energy at a power plant.
Do you agree or disagree?
• What is energy?
• What are potential and kinetic energy?
• How is energy related to work?
• What are different forms of energy?
Forms of Energy
• energy
• kinetic energy
• potential energy
• work
• mechanical energy
Forms of Energy
• sound energy
• thermal energy
• electric energy
• radiant energy
• nuclear energy
• Energy is the ability to cause change.
• Energy can cause changes in the motions of objects.
What is energy?
energy
from Greek energeia, means “activity”
• Kinetic energy is energy due to motion.
• All moving objects have kinetic energy.
• The faster an object moves, the more kinetic energy it has.
• If two objects move at the same speed, the object with more mass has more kinetic energy.
Kinetic Energy—Energy of Motion
The kinetic energy (KE) of an object depends on its speed and its mass. The vertical bars show the kinetic energy of each vehicle.
• Potential energy is stored energy due to the interactions between objects or particles.
• The gravitational potential energy stored between an object and Earth depends on the object’s weight and height.
• Elastic potential energy is energy stored in objects that are compressed or stretched.
Potential Energy—Stored Energy
Chemical potential energy is energy stored in the chemical bonds between atoms.
Potential Energy—Stored Energy (cont.)
In what way are all forms of potential energy the same?
• Work is the transfer of energy that occurs when a force is applied over a distance.
• Work depends on both force and distance.
• You only do work on an object if that object moves.
Energy and Work
The girl does work on the box as she lifts it. The work she does transfers energy to the box. The colored bars show the work that the girl does (W) and the box’s potential energy (PE).
• Energy is the ability to cause change.
• The gravitational potential energy between an object and Earth increases when you lift the object.
• You do work on an object when you apply a force to that object over a distance.
A. electric energy
B. mechanical energy
C. radiant energy
D. thermal energy
Which type of energy is described as the total energy of an object or group of objects due to large-scale motions and interactions?
A. kinetic energy
B. work
C. potential energy
D. electric energy
What is the transfer of energy that occurs when a force is applied over a distance?
A. kinetic energy
B. potential energy
C. sound energy
D. stored energy
Which term refers to energy due to motion?
1. A fast-moving baseball has more kinetic energy than a slow-moving baseball.
2. A book sitting on a shelf has no energy.
Do you agree or disagree?
• What is the law of conservation of energy?
• How does friction affect energy transformations?
• How are different types of energy used?
Energy Transformations
The changes from one type of energy to another type of energy are called energy transformations.
Changes Between Forms of Energy
Changes Between Forms of Energy (cont.)
radiant
Science Use transmitted by electromagnetic waves
Common Use bright and shining; glowing
Energy changes between kinetic energy (KE) and potential energy (PE) when a ball is thrown and moves upward and then downward.
Changes Between Kinetic and Potential Energy
• As the ball moves upward, its speed and kinetic energy decrease, but the potential energy is increasing because the ball’s height is increasing.
• At the ball’s highest point, the gravitational potential energy is greatest, and the ball’s kinetic energy is the least.
• As the ball moves downward, potential energy decreases. At the same time, the ball’s kinetic energy increases.
• When the ball reaches the player’s hand again, its kinetic energy is at the maximum value again.
According to the law of conservation of energy, energy can be transformed from one form into another or transferred from one region to another, but energy cannot be created or destroyed.
The Law of Conservation of Energy
What is the law of conservation of energy?
Friction is a force that resists the sliding of two surfaces that are touching.
The Law of Conservation of Energy (cont.)
friction
from Latin fricare, means “to rub”
• What happens to mechanical energy when you apply the bicycle brakes and the bicycle stops?
• A moving bicycle has mechanical energy. When you apply the brakes, the bicycle’s mechanical energy is not destroyed.
Friction and the Law of Conservation of Energy
• The mechanical energy is transformed into thermal energy. Friction between the brake pad and the moving wheel transforms mechanical energy into thermal energy.
• There is always friction between any two surfaces that are rubbing against each other.
Friction and the Law of Conservation of Energy (cont.)
• When you use energy, you usually change it from one form into another.
• All forms of energy can be transformed into thermal energy.
• During photosynthesis, a plant transforms the Sun’s radiant energy into chemical energy that it stores in chemical compounds.
Using Energy
• When energy changes form, some thermal energy is always released.
• Scientists often refer to thermal energy that cannot be used as waste energy.
• Whenever energy is used, some energy is transformed into useful energy and some is transformed into waste energy.
Using Energy (cont.)
• Energy can change form, but according to the law of conservation of energy, energy can never be created or destroyed.
• Friction transforms mechanical energy into thermal energy.
• Different forms of energy, such as sound and radiant energy, are used when someone talks on a cell phone.
A. electric energy
B. radiant energy
C. thermal energy
D. sound energy
All forms of energy can be transformed into what form of energy?
A. law of conservation of energy
B. friction
C. potential energy
D. energy transformations
What term refers to the changes from one type of energy to another type of energy?
A. chemical energy
B. electric energy
C. kinetic energy
D. thermal energy
During photosynthesis, a plant transforms the Sun’s radiant energy into what type of energy?
3. Energy can change from one form to another.
4. If you toss a baton straight up, total energy decreases as the baton rises.
Do you agree or disagree?
• What are nonrenewable energy resources?
• What are renewable energy resources?
• Why is it important to conserve energy?
Energy Resources
• nonrenewable energy resource
• fossil fuel
• renewable energy resource
• inexhaustible energy resource
Energy Resources
• Almost all the energy you use can be traced back to the Sun.
• A small amount of energy that reaches Earth’s surface comes from inside Earth.
Sources of Energy
• Most of the electric energy you use comes from electric power plants, which transform the energy in an energy source into electric energy.
• One source of energy comes from burning fuels, such as coal.
• Nuclear power plants use the nuclear energy in uranium and hydroelectric power plants convert the kinetic energy in falling water into electric energy.
Electric Power Plants
This coal-burning electric power plant transforms chemical energy stored in a fossil fuel into electric energy.
• A nonrenewable energy resource is an energy resource that is available in limited amounts or that is used faster than it is replaced in nature.
• Fossil fuels are the remains of ancient organisms that can be burned as an energy source.
Nonrenewable Energy Resources
Nonrenewable Energy Resources (cont.)
fossil
from Latin fossilis, means “dug up”
Nonrenewable Energy Resources (cont.)
Why are fossil fuels considered a nonrenewable energy resource?
Nonrenewable Energy Resources (cont.)
• Petroleum and natural gas formed from microscopic ocean organisms that died and sank to the ocean floor.
• The chemical potential energy stored in fossil fuels changes to thermal energy when fossil fuels burn.
• Petroleum, coal, and natural gas are all examples of fossil fuels.
Formation of PetroleumGeologic processes buried these dead organisms under layers of sediment and rock. High temperature and pressure changed them into oil and natural gas.
Nonrenewable Energy Resources (cont.)
• Over the past 100 years, Earth’s surface has warmed by about 0.7°C, which is due, in part, to the increasing amount of carbon dioxide produced by burning fossil fuels.
• In nuclear power plants, breaking apart uranium nuclei transforms nuclear energy into thermal energy.
A nuclear power plant transforms nuclear energy into electric energy.
A renewable energy resource is an energy resource that is replaced as fast as, or faster than, it is used.
Renewable Energy Resources
Contrast renewable and nonrenewable energy resources.
• The most widely used renewable energy resource is falling water.
• A hydroelectric power plant transforms the kinetic energy in falling water into electric energy.
Renewable Energy Resources (cont.)
A hydroelectric power plant converts the potential energy of the water stored behind the dam to electric energy.
• An inexhaustible energy resource is an energy resource that cannot be used up.
• Because the Sun will produce energy for billions of years, solar energy is an inexhaustible energy resource.
• Solar cells can be placed on the roof of a building to provide electric energy.
Renewable Energy Resources (cont.)
• Wind energy is another inexhaustible energy resource.
• Modern wind turbines convert the kinetic energy in wind into electric energy.
• Thermal energy from inside Earth is called geothermal energy.
• In a few places, wells can be drilled to reach geothermal reservoirs.
Renewable Energy Resources (cont.)
A geothermal power plant transforms the thermal energy from inside Earth into electric energy.
• Fossil fuels provide about 85 percent of the energy used in the United States.
• Because the supply of fossil fuels is decreasing, there could be shortages of fossil fuels in the future.
• Conserving energy is one way to reduce the rate at which all energy resources are used.
Conserving Energy Resources
About 93 percent of the energy used in the United States comes from nonrenewable energy resources—fossil fuels and nuclear energy.
Conserving Energy Resources (cont.)
How does conserving energy affect the rate at which energy resources are used?
• Nonrenewable energy resources, such as fossil fuels, are used faster than they are replaced in nature.
• Renewable energy resources are replaced in nature as fast as they are used.
• Conserving energy, such as driving fuel-efficient cars, is one way to reduce the rate at which energy resources are used.
A. nonrenewable energy resource
B. renewable energy resource
C. inexhaustible energy resource
D. alternative energy resource
What is the term for an energy resource that is available in limited amounts or that is used faster than it is replaced?
A. solar energy
B. hydroelectric power
C. geothermal energy
D. fossil fuels
What is the name for thermal energy that comes from inside Earth?
A. about 15 percent
B. about 35 percent
C. about 55 percent
D. about 85 percent
How much of the energy used in the United States comes from fossil fuels?
5. Nuclear power plants release many dangerous pollutants into the air as they transform nuclear energy into electric energy.
6. Thermal energy from within Earth can be transformed into electric energy at a power plant.
Do you agree or disagree?
Key Concept Summary
Interactive Concept Map
Chapter Review
Standardized Test Practice
Energy is the ability to cause change. Energy resources contain energy that can be transformed into other, more useful forms of energy.
• Energy is the ability to cause change.
• Kinetic energy is the energy a body has because it is moving. Potential energy is stored energy.
• Different forms of energy include thermal energy and radiant energy.
Lesson 1: Forms of Energy
Lesson 2: Energy Transformations
• Any form of energy can be transformed into other forms of energy.
• According to the law of conservation of energy, energy can be transformed from one form into another or transferred from one region to another, but energy cannot be created or destroyed.
• Friction transforms mechanical energy into thermal energy.
• A nonrenewable energy resource is an energy resource that is available in a limited amount and can be used up.
• A renewable energy resourceis replaced in nature as fast as, or faster than, it is used.
• Conserving energy, such as turning off lights when they are not needed, is one way to reduce the rate at which energy resources are used.
Lesson 3: Energy Resources
A. energy
B. friction
C. motion
D. work
Which term describes the ability to cause change?
A. thermal energy
B. sound energy
C. radiant energy
D. kinetic energy
Which type of energy is due to the motion of particles that make up an object?
A. friction
B. kinetic energy
C. waste energy
D. work
What is a force that resists the sliding of two surfaces that are touching?
A. waste energy
B. thermal energy
C. radiant energy
D. electric energy
Most of the chemical energy used in cars ends up as what kind of energy?
A. exhaustible energy resource
B. renewable energy resource
C. inexhaustible energy resource
D. nonrenewable energy resource
What term refers to an energy resource that cannot be used up?
A. electric energy
B. mechanical energy
C. radiant energy
D. thermal energy
What is another term for light energy carried by electromagnetic waves?
A. force and mass
B. mass and distance
C. force and distance
D. speed and mass
Work depends on what two factors?
A. Energy can be created and destroyed.
B. Energy can be created, but not destroyed.
C. Energy cannot be created or destroyed.
D. Energy cannot be created, but can be destroyed.
Which is true according to the law of conservation of energy?
A. chemical energy
B. electric energy
C. potential energy
D. thermal energy
Friction between a bicycle’s brake pads and the moving wheels transforms mechanical energy into what kind of energy?
A. solar energy
B. hydroelectric energy
C. fossil fuels
D. inexhaustible energy resources
What are the remains of ancient organisms that can be burned as an energy source?